Connecting structure for connecting a circuit section to a chamber, and fuel cell comprising same

ABSTRACT

Connecting structures made of a tubular metal element. The structure has a tubular metal element which is connected to the orifice of a chamber. The chamber is made of a thin metal sheet. The structure also has a duct shaped connecting member which is sealed onto the other end of the tubular metal element. The structure may be used for producing fuel cells when the plate which forms parallel channels, is a current collector with gas circulating channels in contact with a proton-exchanging membrane.

Connecting structure for connecting a fluid circuit section to achamber, and fuel cell comprising same.

The present invention relates to connecting structures between a fluidcircuit section and a chamber delimited on at least one side by a thinmetal sheet provided with at least one orifice for access to thechamber.

The connection of a tube to a thin metal sheet presents manydifficulties, both in the mechanical strength and the seal, inparticular with metal sheets that are difficult to weld such as alloyedsteels. The difficulties are even greater when the chamber has a greatlyreduced effective internal volume. The problems are further increasedaccording to the fluids concerned, aggressive or oxidizing, as is thecase in particular in fuel cells.

The object of the present invention is to propose a simple, compact andreliable connecting structure, including with very thin metal sheets,less than 0.4 mm, and with greatly reduced chamber volumes.

To do this, according to the invention, the connecting structurecomprises a tubular metal element having a first end set into theorifice of the metal sheet and a second end that can be connected to thecircuit section typically via a connecting member, advantageously madeof plastic, comprising a duct receiving at least the second end of thetubular element and secured in sealed manner to the latter.

According to the more particular features of the invention:

-   -   the element and the metal sheet are made of one and the same        grade of metal, typically of stainless steel,    -   the connecting member comprises an internal chamber that can be        connected to the circuit section.

The present invention also relates to a fuel cell in which the metalsheet forms, by stamping, a series of parallel ducts and is coupled insealed manner to a proton-exchange membrane.

Other features and advantages of the invention will emerge from thefollowing description of embodiments, given for illustrative purposesbut in no way limiting, made in relation to the appended drawings, inwhich:

FIG. 1 is a schematic view in perspective of a half fuel cell showingthe configuration of the stamp-formed metal sheet;

FIG. 2 is an enlarged schematic view in section of a connectingstructure according to the invention, and

FIG. 3 is a top view of two adjacent cells of a fuel cell provided withconnecting structures according to the invention.

FIG. 1 shows a half-cell 1 of a fuel cell in cross-section with itsproton-exchange membrane 2 against which is pressed, with interpositionof a peripheral seal 3, a stamped metal sheet 4 to form undulations 5whose internal peaks bear in sealed manner against the membrane 2thereby to define parallel ducts 6 allowing the gases to circulate alongthe membrane, as indicated by the arrows, the electricity produced beingcarried by the metal of the metal sheet, typically made of stainlesssteel.

To make compact structures, such as that shown in FIG. 3, the metalsheet 4, typically made of stainless steel, has a thickness of less than0.5 mm, typically less than 0.4 mm. The ducts 6 have a height (waveamplitude) of less than 5 mm, typically less than 2 mm. The lateralducts of the metal sheet 4 are each provided, at one of their ends, withan access orifice 7 for the connection to a fluid circuit section 8, thefluid typically being hydrogen on the one hand and a gas mix containingoxygen on the other hand in the case of fuel cells.

In the embodiment shown in FIG. 2, the connecting structure according tothe invention for connecting the fluid circuit section 8 to the orifice7 of the metal sheet 4 comprises a tubular metal element 9, typicallyalso made of stainless steel, with an overall diameter slightly greaterthan that of the orifice 7 and comprising a thinned end 10 of smallaxial extension (of the order of twice the thickness of the metal sheet4) and substantially with the same diameter as that of the orifice 7 inorder to be inserted into the latter with the rear shoulder 11 pressingagainst the outer surface of the metal sheet 4. Then, the protruding endof the thinned end 10, with a thickness lying between 0.05 and 0.5 mm,preferably between 0.1 and 0.3 mm, is set in sealed manner into the hole7, thus fixedly attaching in sealed manner the tubular element 9 to themetal sheet 4.

The connecting structure also comprises a connecting member 12,advantageously made of molded polymer, of a generally elongatedconfiguration, defining an inner tubular chamber 13 having a maindirection culminating at one end in an enlarged diameter connectionorifice 14 and, at the other end, in a duct 15 extending orthogonally tothe chamber. The internal diameter of the duct 15 is slightly greaterthan the external diameter of the tubular element 9 and the latter isforce-fitted into the duct 15 with the application of ultrasounds whichcause a total or partial fusion of the edges of the duct while thusfixedly attaching in sealed manner the tubular element 9 to theconnecting member 12 whose outer face, in which the duct 15 culminates,comes to bear on the outer face of the metal sheet 4. In assembledconfiguration, the chamber 13 extends parallel to the metal sheet 4,beyond the latter, thus making it easy to connect the connecting orificeto the fluid section 8.

In the embodiment shown, the connecting member 12 also comprises a pin16 parallel to the duct 15 which is positioned in a hole 17 formed inthe flat peripheral zone of the metal sheet 4, the pin being deformedwhen hot or by heading to consolidate the positioning and retention ofthe member 12 relative to the metal sheet 4.

The connecting orifice 14 may be of a shape and dimension suitable forallowing any type of sealed connection, advantageously removable, at atube end such as the circuit section 8.

Although the invention has been described in relation to embodiments, itis not limited thereby, but is susceptible to modifications and variantswhich will be evident to those skilled in the art in the context of theclaims hereinafter.

1-10. (canceled) 11-20. (canceled)
 21. An apparatus which may be used asa connecting structure for connecting a fluid circuit section to achamber, said apparatus comprising: a) a tubular metal element, wherein:1) said tubular metal element comprises: i) a first tubular element end;and ii) a second tubular element end; 2) said first tubular element endis connected to the orifice of a chamber; and 3) said chamber comprises:i) at least one side made of a thin metal sheet; and ii) said orifice;and b) a connecting member, wherein: 1) said connecting member comprisesa duct; and 2) said second tubular element end interfaces with, and issealed to, said duct.
 22. The apparatus of claim 21, wherein thethickness of said metal sheet is less than or equal to about 0.4 mm. 23.The apparatus of claim 21, wherein both said metal sheet and saidtubular element are made of substantially the same grade of metal. 24.The apparatus of claim 23, wherein both said metal sheet and saidtubular element are made of stainless steel.
 25. The apparatus of claim21, wherein said connecting member further comprises an internal chambersuitable for connection to a fluid circuit section.
 26. The apparatus ofclaim 25, wherein said connecting member is made of plastic.
 27. Theapparatus of claim 25, wherein: a) said connecting member furthercomprises a protruding portion; and b) said protruding portion issecured to said metal sheet.
 28. The apparatus of claim 25, wherein saidinternal chamber has a main direction which is substantially parallel tosaid metal sheet.
 29. The apparatus of claim 21, wherein: a) said metalsheet is stamped to form a series of parallel ducts; b) said metal sheetis sealed to a membrane in order to form a fuel cell; and c) saidorifice is located near the end of at least one said parallel duct. 30.An apparatus which may be used as a fuel cell, said apparatus comprisinga connecting structure for connecting a fluid circuit section to achamber, said structure comprising: a) a tubular metal element, wherein:1) said tubular metal element comprises: i) a first tubular element end;and ii) a second tubular element end; 2) said first tubular element endis connected to the orifice of a chamber; and 3) said chamber comprises:i) at least one side made of a thin metal sheet; and ii) said orifice;and b) a connecting member, wherein: 1) said connecting member comprisesa duct; and 2) said second tubular element end interfaces with, and issealed to, said duct.
 31. The apparatus of claim 30, wherein thethickness of said metal sheet is less than or equal to about 0.4 mm. 32.The apparatus of claim 30, wherein both said metal sheet and saidtubular element are made of substantially the same grade of metal. 33.The apparatus of claim 30, wherein said connecting member furthercomprises an internal chamber suitable for connection to a fluid circuitsection.
 34. The apparatus of claim 33, wherein: a) said connectingmember further comprises a protruding portion; and b) said protrudingportion is secured to said metal sheet.
 35. The apparatus of claim 30,wherein: a) said metal sheet is stamped to form a series of parallelducts; b) said metal sheet is sealed to a membrane in order to form afuel cell; and c) said orifice is located near the end of at least onesaid parallel duct.